As the battle escalates in the so-called mackerel wars, Mr Coveney said sanctions — which could include a ban on Icelandic fishing boats landing any catch at EU ports — would be in place in the autumn.

Tensions have grown since 2008 when Iceland, which previously caught little of the fish, unilaterally increased its quota after the numbers in its waters increased dramatically — believed to be as a result of warmer waters due to climate change.

After several rounds of negotiations on new quotas, there has been no agreement between the EU, Norway, Iceland and the Faroe Islands who jointly manage the north-east Atlantic mackerel fishery.

Mr Coveney said there was “no serious effort” by either Iceland or the Faroe Islands to come to an agreement, and they are asking for “a ridiculously high level” of access to the stock.

They rejected an EU offer of 15% of the quota.

“Clearly the EU is willing to agree an increased figure if Iceland and the Faroes would respect that and would negotiate on the basis of a realistic quota,” said Mr Coveney.

Mackerel is Ireland’s most valuable fish — worth between €110m and €140m a year to the economy depending on market prices.

It keeps 10 processing factories in business in Galway, Cork, Kerry, and Donegal.

Recognising that the stocks are under threat from over-fishing, Ireland agreed to a 15% reduction in its quota, giving us about 35% of the overall quota.

Iceland and the Faroe Islands, with a combined population of fewer than 370,000, have increased their catch from 5% in 2006 to 52% this year.

Fishing communities here have accused the EU of being too slow to act. And Mr Coveney accepted it needed to “show its teeth” and take a tougher approach.

He said the European Commission will move to impose sanctions. “I would like to see it happen tomorrow but it’s going to take a little bit more time than that. But certainly it has to happen in the autumn,” he told RTÉ radio.

“Otherwise we go into a sixth year of catching mackerel where we have two countries who are blatantly breaking all of the rules, ignoring all the international advice.”

If action is not taken, towns like Castletownbere in West Cork and Killybegs in Donegal could lose valuable mackerel stocks which they are hugely reliant on.

“We could see a collapse in the health of that stock, greatly cutting the amount of mackerel caught.”